JPS6136808Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a tailing pad thrust bearing, which is a type of hydrodynamic gas bearing.

[Conventional technology]

A tailing pad thrust bearing has a plurality of tailing pads, each supported by a pivot, arranged at equal angular intervals around the outer periphery of a rotating shaft, and a plurality of tailing pads each supported by a pivot. The thrust force acting on the rotating shaft is supported by the pressure of the gas film generated between the thrust runner and the end face of the thrust runner.It is mainly used as a bearing for high-speed rotating shafts in turbo machinery, etc. It is used.

However, in the conventional one, the pivot is a long bolt-shaped member having a hemispherical protrusion at the tip for pivotally supporting the tailing pad, and the bolt-shaped pivot is opposed to the end face of the thrust runner. It is screwed into a wall of a housing, etc., or into a screw hole of a pivot support, etc., provided on this wall. Therefore, there is a disadvantage that the pivot portion is bulky and the entire bearing becomes large. Furthermore, since a large number of pivots must be screwed into respective screw holes and their protruding positions must be adjusted individually, there is an inconvenience that assembly and adjustment work is time-consuming. Furthermore, in such a device, the pivot is held fixed in the housing, etc., so in order to set the distance between the tailing pad and the thrust runner to an appropriate value, it is necessary to check the flatness and straightness of each part. There is a problem in that high processing accuracy is required regarding angles, etc., and a large number of man-hours are required for manufacturing. Furthermore, if the pivot is long, it is likely to be affected by thermal strain and the distance between the pivots will fluctuate, making it difficult to use it in locations subject to rapid temperature changes.

Therefore, recently, for example, as shown in Japanese Utility Model Publication No. 46-32488, a plurality of cup-shaped flexures made of elastic members are attached to the fixed wall surface of the housing facing the thrust runner, and each of these flexures is A device has also been developed in which each tailing pad is supported by a hemispherical pivot protruding from the top of the device.

With this construction, the axial dimension of the member supporting the pivot can be reduced, making the bearing more compact as a whole, and preventing the problem of variations in the clearance between the tail tailing pad and the thrust runner caused by thermal distortion. Moreover, because the tail tailing pad can be held elastically, even if there is some error in the parallelism between the thrust runner and the fixed wall surface, or in the flatness of each surface, it is possible to absorb this through the elastic deformation of each flexure, thereby mitigating the problem of uneven clearance between each tail tailing pad and the thrust runner.

[Problem that the invention attempts to solve]

However, if each tailing pad is elastically held by one type of flexure having a predetermined elasticity, various problems may occur depending on the setting of the elastic force. That is, if the flexure is made to have a strong elastic force, problems similar to those occurring when the pivot is fixedly supported are likely to occur. In other words, if there is an error in the parallelism between the thrust runner and the fixed wall facing it, or in the flatness of each surface, or if there is an error in the dimensions of the flexure, each tailing will occur during light load operation when the flexure is difficult to deform sufficiently elastically. The distance between the pad and the thrust runner becomes uneven, which tends to impair the stability of the support. Also,
When using a flexure with strong elasticity, if a foreign object gets caught between a particular tailing pad and the thrust runner, the thrust runner will receive a large reaction force from the foreign object. There is also the disadvantage that temporary fluctuations are caused between the other tailing pads and the thrust runner, making the bearing condition unstable.

On the other hand, if the flexure is made to have weak elasticity, it will not be able to support a large thrust force, resulting in the problem that the so-called load capacity of the bearing will become small.

The present invention aims to solve the various problems explained above all at once.

[Means for solving problems]

In order to achieve this objective, the present invention adds innovation to the pivot and the pivot holding structure, and also elastically supports the pivot using a flexure and a mini-flexure whose elastic force is weaker than that of the flexure. be.

That is, the tailing pad/thrust bearing according to the present invention includes a fixed wall surface that faces one end surface of a thrust runner provided on a rotating shaft via a tailing pad, and a fixed wall surface that is attached to the fixed wall surface and that faces the thrust runner. a pivot holder having a through hole substantially perpendicular to one end surface; a substantially ball-shaped pivot that is fitted into the through hole of the pivot holder and supports the tailing pad; and a pivot holder provided between the pivot holder and the fixed wall surface. a flexure that elastically supports a mating end of the pivot;
The present invention is characterized in that it includes a mini flexure which is inserted between the flexure and the pivot and urges the pivot toward the thrust runner with an elastic force weaker than the elastic force of the flexure.

[Effect]

According to such a configuration, the following effects can be obtained.

First, when the bearing is assembled, each mini-flexure is appropriately bent so that each tailing pad is attached to the thrust runner. In this case, if the elastic force of each mini-flexure is set to a relatively small value, even if there is some error in the parallelism between the thrust runner and the fixed wall or the dimensions of the pivot, each tailing can be There is no significant difference in the force applied to the runner. Therefore, when the shaft rotates and dynamic pressure is generated between each of the tailing pads and the thrust runner, and a gap is formed between them, the gap becomes approximately uniform. Therefore, when the thrust force is relatively small and the load is light, the distance between each tailing pad and the thrust runner is maintained at an appropriate value mainly by the action of this mini-flexure, and a stable bearing condition is maintained. can get. At this time, if a foreign object gets caught between one of the tailing pads and the thrust runner, the mini flexure will bend and evacuate the tailing pad, thereby removing the shock. will be absorbed. Therefore, it is possible to suppress the phenomenon in which a large reaction force acts on the thrust runner due to the intrusion of foreign matter, causing abnormal fluctuations between the thrust runner and other tailing pads, and to prevent disturbances in the support state. can be minimized.

On the other hand, after the thrust force increases and the mini-flexure is deformed to the maximum limit, the flexure is elastically deformed to maintain the above-mentioned distance at an appropriate value. When the load is reduced from this state, the mini-flexure regains its elastic function and performs an adjustment function between the two.

Therefore, even if the load fluctuates over a wide range, a stable bearing condition can always be maintained.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

A fixed wall surface 4 provided on a housing 3 is opposed to one end surface of a flanged thrust runner 2 provided on a rotating shaft 1 in parallel via tailing pads 5. The tailing pad 5 is a fan-shaped plate that faces one end surface of the thrust runner 2 with a small gap C therebetween, and a plurality of tailing pads 5 are attached to the outer periphery of the rotating shaft 1. are arranged at equal angular intervals. A pivot holder 7 for holding ball-shaped pivots 6 supporting the tailing pads 5 is attached to the fixed wall surface 4. The pivot holder 7 is ring-shaped and surrounds the rotating shaft 1, and has through holes 8 perpendicular to one end surface of the thrust runner 2 at portions corresponding to the tailing pads 5. Each of the pivots 6 is fitted into each through hole 8. The pivot holder 7 is attached to the fixed wall surface 4 via a flexure 9, and is fixed to the fixed wall surface 4 using bolts 11, etc. The flexure 9 is a ring-shaped member made of a spring plate or the like, and closes the open end of the through hole 8 on the side opposite to the tailing pad 5. Then, the flexure 9 is attached to a portion of the fixed wall surface 4 corresponding to each of the through holes 8.
A hole 12 is formed in each case so that the material can be elastically deformed in the thickness direction. Further, the pivot 6 fitted into the flexure 9 and each through hole 8
Mini flexures 13 are provided between the thrust runners 1 and 2 to elastically bias each pivot 6 in the direction of the thrust runner 2. Note that this mini flexure 13 is made of a weak spring material having a much smaller elastic modulus than the elastic modulus of the flexure 9.

With this type of structure, the length of the pivot 6, that is, the axial dimension of the pivot 6, can be made much shorter than that of a bolt-shaped bearing, making the entire bearing extremely compact. can do. If the pivot 6 is made short and ball-shaped in this way, it is possible to suppress the problem that the dimension of the pivot 6 changes due to the influence of thermal strain and the above-mentioned distance C fluctuates. It has the advantage of not causing any deterioration in performance even when used in places.

Moreover, the pivot 6... is connected to the flexure 9...
In addition, the mini flexures 13, which have a weaker elastic force than the flexures 9, are also used for elastic support, so that the following effects can be obtained.

First, in the assembled state of the bearing, each mini-flexure 13 is appropriately bent so that each tailing pad 5 is attached to the thrust runner 2.
In this case, since the elastic force of each mini-flexure 13 is set to be relatively small, it is assumed that the parallelism between the thrust runner 2 and the fixed wall surface 4 and the pivot 6
Even if there is some error in the dimensions, etc., there will not be a large difference in the force with which each tailing pad 5 is pressed against the thrust runner 2. Therefore, the rotating shaft 1
rotates, dynamic pressure is generated between each tailing pad 5... and the thrust runner 2, and both 5...
In the state where 〓 C is formed between 2, their 〓
The distance C becomes approximately uniform. Therefore, when the thrust force is relatively small and the load is light, the distance C between each tailing pad 5 and the thrust runner 2 is mainly caused by the action of this mini flexure 13.
is maintained at an appropriate value. Therefore, a stable bearing condition can be obtained without inconveniences such as requiring high accuracy in machining and assembling each component or requiring time and effort in assembling and adjusting.

If a foreign object gets caught between one of the tailing pads 5 and the thrust runner 2 during such light load operation, the corresponding mini flexure 13 will bend and the tailing pad 5 will be evacuated. By letting them do so, they will absorb the shock. Therefore, it is possible to suppress the phenomenon in which a large reaction force acts on the thrust runner 2 due to the intrusion of foreign matter and abnormal fluctuations occur in the distance C between the other tailing pads 5 and the thrust runner 2. Disturbances in the support state can be minimized, making it possible to maintain a stable bearing state. This effect is very beneficial because disturbances in the support state due to foreign objects are likely to occur during light load operation when the thrust force to counter the reaction force from the foreign objects is small.

On the other hand, the thrust force increases and the mini flexure 1
After the flexures 3... are deformed to the limit, the flexures 9... are elastically deformed to maintain the distance C at an appropriate value.

Therefore, with this type of bearing, it is possible to always maintain a stable bearing condition even if the load fluctuates over a wide range, and it is easier and more reliable than when the pivot is elastically supported by a single type of flexure. It is possible to increase the load capacity.

Note that the pivot is not limited to a complete ball shape, but may be a part of a ball cut off, or a hemispherical shape. Further, the flexure is not limited to a disk-shaped one as shown in the illustrated example, but can also be constructed of a coiled spring inserted into the housing, for example. Furthermore, the structure of the mini flexure is not limited to the illustrated example.

[Effect of idea]

As explained above, in the present invention, the pivot is made into a substantially ball-shaped pivot and held in the through hole of the pivot holder, so the axial dimension of the pivot is significantly shorter than that of a bolt-shaped pivot. This makes it possible to make the entire structure more compact, and also has the effect that performance deterioration due to thermal distortion is less likely to occur.

Moreover, since the pivot is elastically supported by a flexure and a mini-flexure whose elastic force is weaker than that of the flexure, the following effects can be obtained.

In other words, if only a flexure with strong elasticity is used, the precision of parts machining must be improved and adjustments must be made carefully to avoid interference between the tailing pad and the thrust runner during light load operation with small thrust force. This leads to inconveniences such as uneven spacing, which makes the bearing condition unstable, and the bearing condition easily disturbed by the intrusion of foreign matter. On the other hand, if only a flexure with weak elasticity is used, it will be inconvenient that it will not be able to support a large thrust force. Therefore, in such conventional bearings, there is a dilemma in that the elastic force of the flexure must be set by sacrificing at least one of the bearing stability during low-load operation and the bearing performance during high-load operation to some extent.

In contrast, with the present invention, the bearing performance during low-load operation can be guaranteed mainly by the mini-flexure, and the performance during high-load operation can be ensured by the flexure, so the above-mentioned dilemma can be reliably resolved. It is possible to do so. Therefore,
It is possible to provide an excellent tailing pad thrust bearing that can always maintain a stable bearing condition even if the thrust force fluctuates greatly.

[Brief explanation of drawings]

FIG. 1 is a front sectional view showing an embodiment of the present invention, and FIG. 2 is a sectional view taken along the line -- in FIG. 1... Rotating shaft, 2... Thrust runner, 4...
Fixed wall surface, 5... Tailing pad, 6...
Pivot, 7...Pivot holder, 8...Through hole, 9...Flexia, 13...Mini flexure.

Claims (1)

[Scope of utility model registration request] a fixed wall surface facing one end surface of a thrust runner provided on a rotating shaft via a tailing pad; a pivot holder attached to the fixed wall surface and having a through hole substantially orthogonal to the one end surface of the thrust runner; A substantially ball-shaped pivot that is fitted into the through hole of the pivot holder and supports the tailing pad, and a flexure that is provided between the pivot holder and the fixed wall surface and elastically supports the fitting end of the pivot. and a mini flexure inserted between the flexure and the pivot to bias the pivot toward the thrust runner with an elastic force weaker than the elastic force of the flexure. Padded thrust bearing.